Because of the extremely high cost and high mortality/morbidity of hip fractures due to osteoporosis, reduction in the frequency of these fractures would be of ever increasing value to an aging population such as the United States. Low doses of flouride, such as are found in drinking water, may provide protection against the development of osteoporosis and hip fractures. To study this hypothesis, and ecologic study of the relationship of hip fracture rates to the level of flouride in drinking water is proposed. Hip fracture rates by community of size 1-50 thousand will be constructed from discharge abstract files of hospitals in Iowa for the period 1976-1981. These files are already in the possession of the principal investigator. These rates will be analyzed in relationship to the concentration of flouride (and other elements) in the drinking water of Iowa communities using univariate and multivariate statistical techniques. All Iowa communities have been surveyed and classified by source of drinking water and concentration of water elements on a twice-yearly basis for several decades. Communities (186) of size 1-50 thousand population with a single stable source of water supply will be used in the study. Iowa, with its unique situation of a geographically stable, socioeconomically uniform population and longstanding, accurate water quality data, provides a fertile ground for this study.